In the dispensing of viscous fluids such as toothpaste and the like, it has heretofore been proposed that dispensing construction be provided that function upon compression of a collapsible chamber to dispense a portion of the viscous fluid. Typical dispensers are shown, for example, in U.S. Pat. Nos. 3,141,580, 3,506,163 and 4,402,431.
The dispenser container shown in U.S. Pat. No. 4,402,431 comprises a piston at one end of the container and a compressible chamber at the other which is actuated by axial displacement to dispense a portion of the contents.
It has also been suggested that the collapsible chamber be provided by a member that closes the container and includes a central tubular portion, circumferentially spaced planar portions extending from the tubular portion to a skirt, vertical ribs between the panels, and arcuate circumferentially spaced ribs on the panels at the juncture of the panels with the skirt.
One of the problems with respect to the collapsible chambers heretofore suggested is that it has been difficult to provide the desired amount of viscous fluid in the limited axial displacement of the chamber. Furthermore, the collapsible portion must be made of a highly elastomeric material which is costly.
Accordingly, among the objectives of the present invention are to provide a dispensing package which provides sufficient deflection in order to achieve the desired amount of dispensing; which is low in cost; and wherein the collapsible part may be formed integrally as a major component of the package.
In accordance with the invention, the dispenser package for viscous fluids comprises a container having one end open and provided with a piston and the other end closed by a compressible chamber defined by a plastic bellows that is deflected by movement of a plunger to dispense a portion of the viscous fluid from the container. The plastic bellows comprises a central tubular portion, a hub extending radially outwardly from the tubular portion, a plurality of circumferentially spaced panels extending transversely and radially from the hub to a peripheral skirt extending axially away from the tubular portion. Integral circumferentially spaced ribs interconnect the panels. Alternate panels extend axially and radially upwardly toward the tubular portion while the remaining panels extend transversely and radially downwardly away from the tubular portion.